Cardiorespiratory and sedative effects of a combination of acepromazine, xylazine and methadone in the horse

Abstract

Summary Cardiorespiratory and sedative effects of a combination of acepromazine, xylazine and methadone were studied in the horse. Acepromazine and xylazine produced cardiovascular effects whereas methadone mainly affected respiratory rate. Decreases in heart rate, arterial blood pressure and respiratory rate were seen. Sedation was superior to that of acepromazine, xylazine or a combination of these. No serious side effects were seen.

Methadone or Butorphanol as Pre-Anaesthetic Agents Combined with Romifidine in Horses Undergoing Elective Surgery: Qualitative Assessment of Sedation and Induction

“…In our study, the respiratory rate was equally significantly reduced from baseline in both groups. A similar effect was already described after methadone when combined with acepromazine and xylazine [ 39 ] and after buprenorphine administration [ 40 ], but values were within the physiological range, possibly reflecting the degree of sedation and lack of any anxiety.…”

“…When considering the cardiovascular effects of methadone in horses, only minimal effects are observed with no physiological or behavioural changes such as excitement, sedation, inhibition of gastrointestinal motility [ 12 , 24 ]. As a sole agent, it increased blood pressure and HR [ 45 ], while when combined with acepromazine and xylazine, a minor influence on these parameters was produced, however AV blocks were recorded up to 65 min [ 39 ]. Moreover, when methadone was administered with detomidine to standing horses, HR significantly decreased after 5 min and second-degree AV blocks were detected but normal synus rhythm was restored within 15 min [ 44 ].…”

Effect of sedation with detomidine and butorphanol on pulmonary gas exchange in the horse

“…A sedated horse must be handled with caution, since it may be aroused by stimulation and can respond with dangerous kicks [ 7 - 9 ]. In a situation in which a painful procedure is planned or local analgesia needs to be placed before surgery on the standing horse, accentuation of both sedation and analgesia can be achieved by adding an opioid to the α 2 -agonist [ 4 , 10 , 11 ]. Butorphanol, a mixed opioid with agonistic and antagonistic properties, has proven effective in such a combination [ 3 , 4 , 12 ].…”

Buprenorphine provides better anaesthetic conditions than butorphanol for field castration in ponies: results of a randomised clinical trial

“…However, in addition to analgesia, opioids play a central role in veterinary medicine, enhancing sedation of a number of sedative agents (Taylor 1985, Taylor and Herrtage 1986, Clarke and Paton 1988); opioids have been used for this purpose in horses for many years (Muir and others 1979, Nilsfors and others 1988, Taylor and others 1988, 2014, Browning and Collins 1994). Butorphanol administered with an α 2 adrenoceptor agonist can be regarded as the ‘default’ opioid/sedative combination widely used for sedation and preanaesthetic medication in horses in current UK equine practice (Taylor and others 1988, Taylor and Clarke 2007, Clarke and others 2014).…”